1. Field of the Invention
The present invention relates to a method for forming a thin-film magnetic recording medium. More particularly, the present invention relates to a method for forming a thin-film magnetic recording medium that facilitates removing foreign particles from a surface of an as-formed protection layer without damaging the protection layer, thereby minimizing signal error.
2. Description of the Related Art
A conventional thin-film magnetic recording medium (hard disk) is disclosed in Japanese Unexamined Laid Open Patent Application No. 2000-200409. This reference discloses a laminate structure including a Cr alloy undercoating layer on a substrate, a Co—Cr alloy nonmagnetic intermediate layer on the undercoating layer, a Co alloy magnetic recording layer on the intermediate layer, a protection layer made mainly of carbon on the magnetic recording layer and a lubricant layer on the carbon protection layer. Many conventional thin-film magnetic recording media do not include an intermediate layer.
Referring now to FIG. 1, a conventional method for manufacturing a conventional thin-film magnetic recording medium involves transferring a substrate 1 into a loading chamber 202 of a thin-film deposition apparatus 201. Thin-film deposition apparatus 201 operates under a vacuum.
Substrate 1 is heated in a vacuum heating chamber 203. Substrate 1 is transferred to an undercoating layer deposition chamber 204. In the undercoat layer deposition chamber 204, an undercoat layer is deposited on substrate 1.
An intermediate layer deposition chamber 205 receives substrate 1 wherein an intermediate layer is deposited on the undercoating layer.
A magnetic recording layer is then deposited on the intermediate layer in a magnetic layer deposition chamber 206. If necessary, a cooling chamber 207 cools the laminate formed so far according to process control parameters.
Next, a protection layer deposition chamber 208 deposits a carbon protection layer. The as-formed laminate is removed from thin-film deposition apparatus 201 into room air by an unloading chamber 209.
Thin-film deposition apparatus 201, which maintains a vacuum atmosphere, includes a substrate holding and a transferring means. Prior to processing, substrate 1 is mounted on the substrate holding and transferring means in loading chamber 202. During operation, substrate 1 is processed from substrate loading chamber 202 to substrate unloading chamber 209 during application of the above-described layers.
After processing in thin-film deposition apparatus 201, the surface of the protection layer of substrate 1 is polished with a polishing tape in a step of tape-polishing 210.
In a step of cleaning 211, foreign particles, the main component of which is carbon, (hereinafter referred to collectively as particles) and micro protrusions on the polished surface of the laminate are removed by washing with pure water or with a solvent.
In a step of lubricant coating 212, a lubricant is coated by spin-coated or dip-coated on the now-cleaned surface of the laminate. The coated lubricant is then fixed onto the protection layer surface in air using an ultraviolet layer or by a heating process. Finally, in a step of surface treatment 214, the surface of the fixed lubricant is burnished with a tape or a head (both not shown) to create a magnetic recording medium 7. The head operates, or flies, at a height of several tens of nanometers (nm) above the surface of the magnetic recording medium and operates to read from and write data to the medium.
The conventional method manufactures magnetic recording medium 7 through a complex and burdensome process. If the particles remaining on the as-deposited protection layer are not removed in advance of the step of surface treatment 214, (coating and burnishing the lubricant layer), the head (not shown) will collide with the protrusions on the surface of the lubricant layer caused by the remaining particles. This causes either the head or the magnetic recording medium 7 (or both) to be damaged.
To prevent this damage, the laminate, including the as-deposited carbon protection layer, is removed from the vacuum and any particles remaining on the as-deposited carbon protection layer are removed by tape polishing. Thereafter, the surface of the carbon protection layer is washed with pure water or with a solvent. After removing the remaining particles as much as possible, the lubricant layer is coated.
Unfortunately, any conventional manufacturing method that includes the step of tape-polishing, are necessarily rolls particles in and on the surface of the carbon protection layer, thereby damaging the surface of the carbon protection layer and causing further damage and stress concentrators.
During the step of cleaning the carbon protection layer in the air, oxidation, nitridation, water absorption, and other chemical and physical problems are caused in the surface of the carbon protection layer by exposure to air before the step of coating the lubricant layer. As a result, the surface of the carbon protection layer is modified, the adhesion of the carbon protection layer and the lubricant layer is adversely affected and the quality of the magnetic recording medium is greatly impaired.